#include <bits/stdc++.h>
#define eps 1e-12
using namespace std;
ifstream in("infasuratoare.in");
ofstream out("infasuratoare.out");
struct point{double x,y;} a[120004],st[120004],st2[120004];

bool cmp(point a, point b)
{
    if(a.x!=b.x) return a.x<b.x;
    else return a.y<b.y;
}

double cross_product(point o, point a, point b)
{
    a.x-=o.x;
    a.y-=o.y;
    b.x-=o.x;
    b.y-=o.y;
    return (a.x*b.y-a.y*b.x);
}
int viz[120002];
int main()
{int n,i,vf=0;
    in>>n;
    for(i=1;i<=n;i++)
    {
        in>>a[i].x>>a[i].y;
    }
    sort(a+1,a+n+1,cmp);
    st[1]=a[1];
    st[2]=a[2];
    vf=2;
    for(i=3;i<=n;i++)
    {
        while(vf>=2&&cross_product(st[vf-1],st[vf],a[i])<eps)
        {
            vf--;
        }
        st[++vf]=a[i];
    }
    int vf2;
    st2[1]=a[n];
    st2[2]=a[n-1];
    vf2=2;
    for(i=n-2;i>=1;i--)
    {
        while(vf2>=2&&cross_product(st2[vf2-1],st2[vf2],a[i])<eps)
        {
            vf2--;
        }
        st2[++vf2]=a[i];
    }
    out<<vf+vf2-2<<'\n';
    for(i=1;i<=vf;i++)
        out<<setprecision(6)<<fixed<<st[i].x<<" "<<st[i].y<<'\n';
    for(i=2;i<vf2;i++)
        out<<setprecision(6)<<fixed<<st2[i].x<<" "<<st2[i].y<<'\n';
    return 0;
}